Mechanism for, and method of, attaching a lead conductor cable to a lead electrode

ABSTRACT

A cardio electrotherapy lead is disclosed herein. In one embodiment, the lead includes a tubular body, a conductor cable and an electrode. The conductor cable longitudinally extends through the tubular body and includes a distal end. The electrode is located on the tubular body and includes an attachment mechanism mechanically coupling the lead distal end to the electrode.

FIELD OF THE INVENTION

The present invention relates cardio electrotherapy leads and methods ofmanufacturing such leads. More particularly, the present inventionrelates to mechanisms for, and methods of, attaching a lead cableconductor to a lead electrode.

BACKGROUND OF THE INVENTION

Leads for administering cardio electrotherapy (e.g., pacing and/ordefibrillation) have tubular bodies with electrodes forming a portion ofthe circumferential outer surface of the lead and/or a portion of thedistal end of the lead. The electrodes are used for sensing, pacingand/or defibrillation. Electrodes for over-the-wire leads come in avariety of shapes including rings, coils, studs/bumps, helical springtips, etc. Regardless of the shape of the electrode, the electrode mustbe electrically hardwired to a conductor cable extending through thelead body from the pacemaker and/or defibrillator.

It is clinically advantageous to decrease the size of electrodes toimprove trackability over guidewires and to lower sensing, pacing anddefibrillation thresholds through higher current densities. For example,with respect to ring electrodes, the length of the ring electrode alongthe longitudinal length of the lead body is shortened to improvetrackability and raise current density.

Conductor cables have typically been electrically hardwired toelectrodes via welding the cable directly to the electrode or using ashort crimp slug welded to the electrode. These methods of hardwiring acable to an electrode have several disadvantages. First, the weld zoneof the cable and the electrode has a decreased fatigue life. Second, thecable can withstand only a reduced pull force due to thereduced/compressed length of a short crimp slug. Third, the methodsincrease the complexity of tooling and manufacturing. Fourth, as it isadvantageous from a manufacturing perspective to minimize the profile ofa cable to electrode attachment to aid assembly, the magnitude of thethree preceding disadvantages is increased.

There is a need in the art for an attachment configuration and a methodof attachment that facilitates the ease of connection between a cableconductor and a lead electrode. There is also a need in the art for anattachment configuration and a method of attachment that increases theintegrity of a connection between a cable conductor and a leadelectrode.

SUMMARY

A cardio electrotherapy lead is disclosed herein. In one embodiment, thelead includes a tubular body, a conductor cable and an electrode. Theconductor cable longitudinally extends through the tubular body andincludes a distal end. The electrode is located on the tubular body andincludes an attachment mechanism mechanically coupling the lead distalend to the electrode.

A method of manufacturing a cardio electrotherapy lead is disclosedherein. In one embodiment, the method includes mechanically attaching adistal end of a cable conductor of the lead to an electrode of the lead.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. As will be realized, theinvention is capable of modifications in various aspects, all withoutdeparting from the spirit and scope of the present invention.Accordingly, the drawings and detailed description are to be regarded asillustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a distal end elevation of the electrode.

FIG. 2 is a top plan view of the electrode as viewed from the directionof arrow A in FIG. 1.

FIG. 3 is a sectional view of the electrode as taken along section line3-3 in FIG. 1.

FIG. 4 is a distal end isometric view of the electrode coupled to thecable conductor 15.

FIG. 5 is a sectional view of the electrode coupled to the cableconductor as taken along section line 3-3 in FIG. 1.

DETAILED DESCRIPTION

The present application describes a system and method for coupling anelectrode 10 for a cardio electrotherapy lead to a cable conductor 15extending through the lead. The electrode 10 has an attachment mechanism20 integral to the electrode 10. The attachment mechanism 20 isconfigured to receive and snap-fit/compression-fit/friction-fit with anattachment feature 25 of the cable conductor 15 to couple the cableconductor 15 to the electrode 10.

The system and method for coupling the electrode 10 to the cableconductor 15 is advantageous for at least the following reasons. First,the system and method simplifies the process involved with forming aconnection between the cable conductor 15 and the electrode 10. Second,the system and method increases the reliability of the connection formedbetween the cable conductor 15 and the electrode 10.

For a detailed discussion of the system and method of coupling anelectrode 10 to a cable conductor 15, reference is made to FIGS. 1-5.FIG. 1 is a distal end elevation of the electrode 10. FIG. 2 is a topplan view of the electrode as viewed from the direction of arrow A inFIG. 1. FIG. 3 is a sectional view of the electrode 10 as taken alongsection line 3-3 in FIG. 1. FIG. 4 is a distal end isometric view of theelectrode 10 coupled to the cable conductor 15. FIG. 5 is a sectionalview of the electrode 10 coupled to the cable conductor 15 as takenalong section line 3-3 in FIG. 1.

As depicted in FIGS. 1-5, in one embodiment, the electrode 10 is a ringelectrode 10 having a cylindrical wall 27 with an inner circumferentialsurface 30, an outer circumferential surface 35, a proximal edge 40, anda distal edge 45. When the ring electrode 10 is mounted on the tubularbody of a lead, the inner circumferential surface 30 extends about thecircumference of the tubular body, the outer circumferential surface 35forms a portion of the outer circumferential surface of the of the leadtubular body, the proximal edge 40 faces towards the proximal end of thelead tubular body, and the distal edge 45 faces towards the distal endof the lead tubular body.

As shown in FIGS. 1 and 3-5, the attachment mechanism 20 is a portion ofthe electrode cylindrical wall 27 that protrudes radially inward fromthe inner circumferential surface 30 of the cylindrical wall 27. In oneembodiment, the attachment mechanism 20 appears as approximatelytwo-thirds to three-quarters of a cylinder protruding radially inwardfrom the inner circumferential surface 30 of the cylindrical wall 27. Inother embodiments, the attachment mechanism 20 will have otherappearances.

As indicated in FIGS. 2 and 3, in one embodiment, the attachmentmechanism 20 includes a radial hole 50 that is centered transverselyrelative to a longitudinal center axis of the attachment mechanism 20and extends radially completely through the cylindrical wall 27 and theattachment mechanism 20. In other words, as depicted in FIG. 3, theradial hole 50 daylights completely through the outer circumferentialsurface 35 of the cylindrical wall 27 and the most radially inwardsurface of the attachment mechanism 20.

As shown in FIGS. 1 and 3, in one embodiment, the attachment mechanism20 includes a proximally extending hole 55 that is centered such thatits center axis coincides with the center axis of the radial hole 50.The center axis of the proximally extending hole 55 is parallel to thelongitudinal axis 57 of the electrode ring 10. The proximally extendinghole 55 extends proximally from the distal face 60 of the attachmentmechanism 20 and through the radial hole 50 until reaching the proximalwall of the radial hole 50.

As indicated in FIGS. 1 and 3, in one embodiment, the attachmentmechanism 20 includes a distally extending hole 65 that is centered suchthat it is coaxially oriented relative to the proximally extending hole55. Thus, the center axis of the distally extending hole 65 is parallelto the longitudinal axis 57 of the electrode ring 10. The distallyextending hole 65 extends distally from the proximal face 70 of theattachment mechanism 20 until reaching the proximal wall of the radialhole 50 where the distally extending hole 65 transitions via a chamfer75 to nearly the diameter of the of the proximally extending hole 55.

As shown in FIGS. 1, 3 and 4, a slot 80 extends radially towards thelongitudinal center axis 57 of the electrode ring 10 from the innercircumferential surface of the proximally extending hole 55. The slot 80also extends distally from the circumferential surface of the radialhole 50 to the distal face 60 of the attachment mechanism 20. Thus, ascan be understood from FIG. 4, the circumferential surface of theproximally extending hole 55 can expand via the slot 80 to allow theattachment feature 25 of the conductor cable 15 to be received at theintersection of the holes 50, 55, 65, as shown in FIG. 5.

As shown is FIGS. 4 and 5, the distal end 85 of the conductor cable 15couples with the electrode 10. The conductor cable 15 extends throughthe lead body between the electrode 10 and the proximal end of the lead.The conductor cable 15 includes a conductive core 90 and an electricallyinsulative jacket 95 extending about the core 90. The jacket 95terminates as it nears the distal end of the conductor cable 15, therebyexposing the core 90. The core 90 extends distally from the terminationof the jacket 95 to terminate at its extreme distal end as theattachment feature 25. In one embodiment, the attachment feature 25 isball-like in shape. In other embodiments, the attachment feature 25 hasother shapes (e.g., cylinder-like, egg-like, etc.).

In one embodiment, the core 90 and its attachment feature 25 are formedfrom stainless steel, platinum, platinum-iridium, gold, MP35N, etc. Inone embodiment, the jacket 95 is formed from a polymer material such asETFE, silicone, parylene, etc.

As illustrated in FIGS. 4 and 5, the conductor cable 15 couples to theelectrode 10 by the attachment feature 25 being received in theattachment mechanism 20 such that the ball-like attachment feature 25occupies the intersection 100 of the holes 50, 55, 65. The proximal sideof the ball-like attachment feature 25 seats against the chamfer or seat75 and the core 90 extends distally therefrom through the distallyextending hole 65.

As can be understood from FIGS. 4 and 5, when the attachment feature 25is received in the attachment mechanism 20, the attachment feature 25occupies the space 100 between a distal entry portion 101 of theattachment mechanism and a proximal backstop portion 102 of theattachment mechanism. The distal entry portion 101 is configured toallow the attachment feature 25 to enter the attachment mechanism 20 andprevent distal displacement of the attachment feature 25 once it hasbeen received within the attachment mechanism 20. The proximal backstopportion 102 prevents further proximal displacement of the attachmentfeature 25 once received within the attachment mechanism 20.

As can be understood from FIGS. 1 and 3-5, to cause the ball-likeattachment feature 25 to be received in the attachment mechanism 20, theproximal end of the conductor cable 15 is proximally fed through theproximally extending hole 55, the intersection 100 and the distallyextending hole 65. The conductor cable 15 continues to be fed proximallyuntil the ball-like attachment feature 25 abuts against the entrance ofthe proximally extending hole 55 at the distal face 60 of the attachmentmechanism 20. The conductor cable 15 is further proximally fed such thatthe sides of the slot 80 are forced apart to increase the diameter ofthe proximally extending hole 50 to accommodate the larger diameterball-like attachment feature 25. In other words, the proximallyextending hole 50 deforms via the expansion of the slot 80 to allow theball-like attachment feature 25 to pass through the proximally extendinghole 50.

Once the ball-like attachment feature 25 passes through the proximallyextending hole 55 and occupies the intersection 100, the proximallyextending hole 50 snaps or otherwise returns to its non-deformed state,thereby preventing the larger diameter ball-like attachment feature 25from distally exiting out of the attachment mechanism 20. Once theball-like attachment feature 25 occupies the intersection 100, theattachment feature 25 seats against the chamfer or seat 75. Furtherproximal displacement of the attachment feature 25 is prevented becausethe diameter of the ball-like attachment feature 25 exceeds the diameterof the distally extending hole 65 and the distally extending hole 65will not deform as the proximally extending hole 55.

As can be understood from FIGS. 4 and 5, the attachment mechanism 20provides a friction-fit/snap-fit/compression-fit type of attachment tothe attachment feature 25 of the conductor cable 15. Thus, a conductorcable 15 can be quickly, easily and securely coupled to an electrode 10.The attachment mechanism 20 provides a low profile attachmentconfiguration that does not have the stress issues associated withwelding.

In one embodiment, the radial hole 50 has a diameter D₁ of betweenapproximately 0.002 inch and approximately 0.025 inch, the proximallyextending hole 55 has a diameter D₂ of between approximately 0.003 inchand approximately 0.020 inch, the distally extending hole 65 has adiameter D₃ of between approximately 0.002 inch and approximately 0.015inch, the slot 80 has a width W of between approximately 0.001 inch andapproximately 0.015 inch, and the attachment feature 25 has a diameterD₄ of between approximately 0.003 inch and approximately 0.025 inch.

In one embodiment, the diameter D₄ of the ball-like attachment feature25 is between: approximately 10 percent and approximately 40 percentlarger than the diameter D₁ of the radial hole 50; approximately 5percent and approximately 20 percent larger than the diameter D₂ of theproximally extending hole 55 when the proximally extending hole 55 is inthe unexpanded or non-deformed state; and approximately 10 percent andapproximately 90 percent larger than the diameter D₃ of the distallyextending hole 65, which is large enough to allow the proximal passageof the conductor cable 65.

In one embodiment, the chamfer 75 is made at an angle of betweenapproximately 10 degrees and approximately 60 degrees relative to thecenter axis of the distally extending hole 65. Thus, the chamfer 75generally matches the outer circumferential surface of the ball-likeattachment feature 25 and serves as a seat 75 for the ball-likeattachment feature 25.

In one embodiment, the attachment mechanism 20 is an integral portion ofthe electrode 10. In one embodiment, the attachment mechanism 20 iscast, machined or otherwise formed with the electrode 10.

While the system and method of coupling an electrode 10 to a cableconductor 15 is described above with respect to the electrode 10 being aring electrode, in other embodiments, as readily understandable by thoseskilled in the art, the electrode 10 will have other configurationswithout departing from the spirit of the invention disclosed herein. Forexample, in other embodiments, the electrode 10 is a helical coil,stud-shaped, crescent (half ring), etc.

Although the present invention has been described with reference topreferred embodiments, persons skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

1. A cardio electrotherapy lead comprising: a tubular body including aproximal end and a distal end; a conductor cable longitudinallyextending through the tubular body and including a proximal end and adistal end, and an attachment member disposed at the distal end of theconductor cable; and an electrode on the tubular body, the electrodeincluding an attachment mechanism mechanically coupling the attachmentmember to the electrode; wherein the attachment mechanism includes alumen having a wall at least partially defining a distal hole extendingproximally and a proximal hole extending distally in communication withthe distal hole, the distal hole and the proximal hole configured toallow the conductor cable to be proximally fed firstly through thedistal hole and secondarily through the proximal hole, and the distalhole sized to allow the attachment member to pass therethrough and theproximal hole sized to prevent the attachment member to passtherethrough.
 2. The lead of claim 1, wherein the wall includes atransverse hole that intersects at least one of the proximal and distalholes to form an intersection that receives the attachment member. 3.The lead of claim 2, wherein the intersection includes a seat thatincludes a surface that generally conforms to a surface of theattachment member.
 4. The lead of claim 3, wherein the seat comprises achamfer coaxial with the proximal hole.
 5. The lead of claim 4, whereinthe chamfer is coaxial with at least the proximal hole.
 6. The lead ofclaim 2, wherein the attachment mechanism further includes a slotmeeting the distal hole, thereby allowing the distal hole to resilientlyincrease in width as the attachment member passes through the distalhole to be received by the intersection.
 7. The lead of claim 2, whereinan axis of the distal hole and an axis of the proximal hole aregenerally parallel to a longitudinal axis of the tubular body and anaxis of the transverse hole is generally perpendicular to the axis ofthe tubular body.
 8. The lead of claim 2, wherein the transverse holeextends at least partially into an opposite wall at least partiallydefining the distal and proximal holes.
 9. The lead of claim 1, wherein,when the attachment member is received in the attachment mechanism, theattachment member resides between a proximal backstop portion and adistal entry portion.
 10. The lead of claim 9, wherein the distal entryportion includes a slotted opening.
 11. The lead of claim 9, wherein thedistal entry portion deforms to facilitate the attachment member beingreceived in the attachment mechanism.
 12. The lead of claim 1, whereinthe electrode is a ring electrode including an inner surface, theattachment mechanism extends inwardly from the inner surface.
 13. Thelead of claim 12, wherein the attachment mechanism is formed at leastpartially by a wall of the electrode.
 14. The lead of claim 1, wherein awidth of the attachment member is greater than a width of the conductorcable, and a width of the proximal hole is less than the width of theattachment member but not less than the width of the conductor cable.15. The lead of claim 14, wherein a width of the distal hole is greaterthan the width of the proximal hole.
 16. The lead of claim 15, whereinthe attachment mechanism receives the attachment member in a snap-fit,compression-fit, or friction-fit provided at least in part by theportion of the distal hole.
 17. The lead of claim 1, wherein theattachment mechanism extends radially toward a longitudinal axis of thetubular body from the electrode.
 18. The lead of claim 1, wherein atleast a portion of the distal hole is configured to allow the attachmentmember to pass, and at least a portion of the proximal hole isconfigured to prevent the attachment member from passing through theproximal hole.
 19. The lead of claim 18, wherein the portion of thedistal hole is configured to allow the attachment member to pass byresiliently increasing in width as the attachment member passes.
 20. Thelead of claim 19, wherein the portion of the distal hole is configuredto return to a width less than a width of the attachment member afterthe attachment member passes.
 21. The lead of claim 18, wherein the wallincludes a gap at the portion of the distal hole.
 22. The lead of claim21, wherein the gap comprises a longitudinal slot.
 23. The lead of claim22, wherein the further comprising a transverse hole in the wall at aproximal end of the longitudinal slot, the lateral hole including awidth greater than a width of the longitudinal slot.